1. Field of the Invention
The present invention relates to a terminal for a flat cable which is excellent in electrical connectability, and can achieve an enhanced efficiency of a connecting operation.
The present application is based on Japanese Patent Application No. 2000-41500, which is incorporated herein by reference.
2. Description of the Related Art
Various flat cable terminals have heretofore been proposed.
FIGS. 5 and 6 show one such terminal disclosed, for example, in Unexamined Japanese Patent Publication No. Hei. 10-275642. This flat cable terminal 51 is formed by bending a single metal sheet, and includes a male terminal portion 52, formed at one end of a base 53a of a strip-like shape, a bottom plate portion 53, formed at the other longitudinal end portion of the base 53a so as to support a flat cable 40 thereon, and a plurality of barrels 54 which extend from opposite side edges of the bottom plate portion 53 in a direction substantially perpendicular to the direction of the length of the base 53a, and can be curved inwardly into a substantially-cylindrical shape so that these barrels 54 can press the flat cable 40 against the bottom plate portion 53 by their outer peripheral surfaces.
In this terminal 51, recesses 55 are formed respectively in those portions of the bottom plate portion 53 corresponding respectively to the barrels 54, and are recessed in a direction substantially perpendicular to the direction of the length of the base 53a as shown in FIG. 6, each of the recesses 55 having substantially the same curvature as that of the distal end portion of the curved barrel 54. Thanks to the provision of these recesses 55, the barrels 54, pressed against the flat cable 40, are kept retained respectively in the recesses 55 even when an external tensile load acts on the flat cable 40 in the longitudinal direction, and therefore the cable 40 is prevented from being disengaged from the terminal 51. And besides, each recess 55 serves to increase the area of contact between the outer peripheral surface of the barrel 54 and the cable 40, thereby enhancing the reliability of the electrical connection.
The flat cable 40 has a plurality of juxtaposed elongate conductors 41 (serving as circuit members) formed on a base sheet 42 which is comprised of, for example, an insulative resin film. For connecting the terminal 51 to the flat cable 40, a distal end portion of the flat cable 40 to be connected to the terminals 51 is processed into juxtaposed rectangular sections by cutting off those portions of the base sheet 42 each disposed between the adjacent conductors 41. Then, the distal end portion of the cable, thus divided into the sections each having the conductor 41 formed thereon, is placed on the bottom plate portions 43 of the terminals 51, and in this condition the barrels 54 of each terminal are pressed to be deformed, thereby achieving the above connection. The flat cable 40 is pressed and held between each recess portion 55, formed in the bottom plate portion 53, and the outer peripheral surface of the corresponding barrel 54, and therefore is electrically and mechanically connected to the terminal 51.
In the above conventional flat cable terminal 51, however, it is necessary to strictly control the curved shape and height of the barrels 54 in order that the contacted condition of the barrels 54 can always be made stable so as to achieve the good press-contact thereof with the flat cable 40 even when the conductor 41 and the base sheet 42 are changed in thickness. However, it has been difficult to strictly control the curved shape and height of the barrels 54. Therefore, there was encountered a problem that the mechanical and electrical connection of the barrel to the cable 40 was weak, or was too strong, so that the cable was disengaged and damaged.
And besides, for connecting the terminals 51 to the distal end portion of the flat cable 40, this distal end portion must be processed into the juxtaposed rectangular sections, and this invited a problem that the efficiency of the connecting operation was low.
The present invention has been made under the above circumstances, and an object of the present invention is to provide a flat cable terminal which can always achieve a stable mechanical and electrical connection with a predetermined contact load, and can achieve an enhanced efficiency of a connecting operation.
To achieve the above object, according to the first aspect of the present invention, there is provided a terminal which comprises a bottom plate portion onto which a flat cable is attachable, at least one barrel formed on the bottom plate portion, and at least one resilient piece portion resiliently deformable on the bottom plate portion, wherein the bottom plate portion is partially cut to form the at least one resilient piece portion, wherein the at least one resilient piece portion is upwardly raised relative to the bottom plate portion, and wherein the at least one barrel pierces a base sheet of the flat cable in a thickness direction thereof, and is so folded that a conductor formed on the base sheet of the flat cable is pressed and held between the at least one barrel and the at least one resilient piece portion.
The flat cable is placed on the bottom plate portion, with the conductor of the flat cable opposed to the bottom plate portion. Then, when the flat cable is pressed toward the bottom plate portion, the barrel pierces the base sheet of the flat cable in the thickness direction thereof, and projects from the rear surface of the flat cable. Then, when the barrel is bent and folded inwardly relative to the bottom plate portion, the flat cable is resiliently held between the barrel and the corresponding resilient piece portion.
According to the second aspect of the present invention, it is preferable that a fine projection is formed on the at least one resilient piece portion in order to firmly press against the conductor of the flat cable. Accordingly, the terminal can be positively electrically connected to the conductor even if the bent barrel is not always held in substantially parallel relation to the bottom plate portion.
According to the third aspect of the present invention, it is preferable that a distal end of the at least one barrel is chamfered so as to facilitate penetration of the at least one barrel relative to the base sheet of the flat cable. That is, the barrel can easily pierce the base sheet of the flat cable.
According to the fourth aspect of the present invention, it is preferable that the at least one barrel has a substantially parabolic shape, so that the at least one barrel can more easily pierce the base sheet of the flat cable.
According to the fifth aspect of the present invention, it is preferable that the flat cable is held between the at least one barrel and the at least one resilient piece portion, so that the at least one resilient piece portion is electrically connected to the conductor of the flat cable.
According to the sixth aspect of the present invention, the conductor of the flat cable may be arranged along a longitudinal direction of the bottom plate portion.
According to the seventh aspect of the present invention, it is preferable that the at least one resilient piece portion is disposed correspondingly to the at least one barrel.
According to the eighth aspect of the present invention, a proximal end of the at least one resilient piece portion may be located adjacent to a proximal end of the at least one barrel.
According to the ninth aspect of the present invention, it is preferable that the at least one resilient piece portion is formed on the bottom plate portion in a cantilever manner.
According to the tenth aspect of the present invention, the terminal may further comprises a terminal body, and a terminal portion formed at a first end portion of the terminal body, wherein the bottom plate portion is formed at a second end portion of the terminal body.
According to the eleventh aspect of the present invention, the plurality of barrels may be arranged on opposite side edges of the bottom plate portion in a staggered manner. In this case, the plurality of resilient piece portions are preferably disposed correspondingly to the plurality of barrels, respectively.
According to the twelfth aspect of the present invention according to the eleventh aspect, proximal ends of the plurality of resilient piece portions may be respectively located adjacent to proximal ends of the plurality of barrels.